The present invention relates generally methods and compositions for control of microbial pathogens.
Species of Xanthomonas (Xanthomonas spp.) are responsible for major agricultural diseases. For example, members of the Brassicaceae, which includes broccoli, cabbage and other plants, are susceptible to black rot, which is caused by Xanthomonas campestris pathovar campestris (Xcc); members of the Solanaceae, which includes tomatoes and peppers, are susceptible to bacterial spot, which is caused by X. campestris pathovar vesicatoria (Xcv); and rice is subject to bacterial leaf blight, which is caused by X. oryzae pathovar oryzae (Xoo). Many other important commercial crops are susceptible to diseases caused by Xanthomonas spp., including wheat, soybean, walnut, mango, peach and many ornamental crops.
Xcc is also known to be closely related to another pathogenic bacterial species, Xylella fastidiosa (Xf), which causes citrus variegated chlorosis, almond leaf scorch and Pierce's disease of grape. Again, several other important commercial crops are susceptible to diseases caused by Xylella spp., including almonds, peaches, plums, alfalfa, citrus, oak, maple, coffee and oleander. Pierce's disease, as a particular example, is a chronic problem in the grape industry in California, greatly exacerbated due to the introduction of the glassy-winged sharpshooter, which is a very effective vector of the Xf pathogen. The management of this disease is particularly problematic since vector control has not proven effective, and the nature of the colonization of grapevines by the pathogen limit the utility of bactericides in killing the pathogen and make strategies of disease control based on other bacterial diseases ineffective.
Improved methods and compositions for control of Xanthomonad, Xylella, and related microbial pathogens are needed.